New roles for chemoreceptor paralogues in Drosophila

描述(申请人提供)：这项工作旨在以果蝇黑腹果蝇为模型，确定寒冷检测的分子机制。感觉系统在人类健康中起着关键作用。人类感觉系统功能障碍不仅与疾病有关，温度的检测对人类疾病媒介昆虫的生存和寻找宿主行为也很重要。目前，我们对昆虫温度检测的分子认识还很有限：昆虫的冷受体尚未见报道。我们的初步数据表明，两个离子亲和性受体家族成员IR21a和IR25a参与了冷感觉。离子亲和性受体(IRS)是无脊椎动物(果蝇有66个IRS)中iGluRs的一个亚家族，它不是谷氨酸依赖的突触传递的媒介，而是酸和胺的化学感受器。我们建议测试IR21a和IR25a的特定亚型通过作用于Arista和/或Labellum的冷感应器来驱动避寒的假设。通过细胞特异性的抢救实验，我们建议确定IR21a和IR25a的哪两种亚型介导了冷回避，并测试这些IR在冷感受器中的表达是否对冷避免是必要的和/或必需的。我们还将测试IR21a和IR25a是否介导了冷感觉。利用钙成像和电生理学的结合，我们将通过检测每组冷传感器在缺乏这些蛋白质的突变体中的冷反应如何改变，来研究IR21a和IR25a对冷感知的贡献。我还将测试IR21a和IR25a是否通过在苍蝇中异位表达这些蛋白以及在青蛙卵母细胞和培养的哺乳动物细胞中异源表达来形成寒冷受体。这些研究将有助于对冷接受的理解和认同。 对阐明这些受体所涉及的分子机制具有极其重要的意义。

DESCRIPTION (provided by applicant): This work aims to identify the molecular mechanisms of cold detection, using the fruit fly Drosophila melanogaster as a model. Sensory systems play key roles in human health. Not only is human sensory system dysfunction associated with disease, the detection of temperature is important for the survival and host-seeking behavior of insect vectors of human disease. At present, our molecular understanding of temperature detection in insects is limited: insect cold receptors have not been reported. Our preliminary data suggest two Ionotropic Receptor family members, IR21a and IR25a, are involved in cold sensing. Ionotropic receptors (IRs) are a subfamily of iGluRs in invertebrates (Drosophila has 66 IRs) known to act not as mediators of glutamate- dependent synaptic transmission, but as chemoreceptors for acids and amines. We are proposing to test the hypothesis that specific isoforms of IR21a and IR25a drive cold avoidance by acting in the cold sensors of the arista and/or labellum. Using cell-specific rescue experiments, we propose to determine which IR21a and IR25a isoforms mediate cold avoidance, and to test whether expression of these IRs in cold sensors is necessary and/or required for cold avoidance. We will also test if IR21a and IR25a mediate cold sensing. Using a combination of calcium imaging and electrophysiology, we will examine the contribution of IR21a and IR25a to cold sensing by examining how the cold-responsiveness of each set of cold sensors is altered in mutants lacking these proteins. I will also test whether IR21a and IR25a act forming a cold receptor by ectopic expression of these proteins in the fly and by heterologous expression in frog oocytes and in cultured mammalian cells. These studies will contribute for the understanding of cold-reception and the identification of the receptors will be extremely significant to elucidate the molecular mechanisms involved.